The existence of an implicit secrecy agreement depends on the commercial inter­relationship between and the commercial interests of the companies involved. These were the decisive points at issue in the case before the board in T 913/01 (see also T 830/90, OJ 1994, 713, T 782/92, T 37/98).

In T 1085/92 the board took the view that, where contractual relations and development agreements existed, a secrecy agreement could be assumed to exist.

In T 1168/09, two prior uses were alleged: the supply of 170 ESG 400 control units and the supply of 111 143 ESG 300/600 control units. No information had been submitted with regard to the conditions of supply and, in particular, as to whether or not confidentiality had been agreed. The board therefore investigated whether, in the light of the business relationship between the supplier and the customer, it had to be presumed that an obligation to maintain secrecy had been tacitly agreed. A tacit obligation to maintain secrecy could be presumed, for instance, where business partners had a shared interest in confidentiality. However, such an interest could only be presumed until the parts had been supplied for serial production because, from then on, the parts were destined to be fitted in cars for sale and so made available to the public. In other words, a shared interest in confidentiality could no longer be presumed once parts had been delivered for serial production (see T 1512/06). In the case at hand, the board found that the large number of control units supplied suggested that they had not been test units. It therefore held that they had been publicly available.

In T 838/97 the board held that an agreement which ruled out availability to the public did not necessarily have to be a contract made in writing, as an implicit or implied agreement could also be taken into account (see e.g. T 818/93, T 830/90).

In T 2/09board took the view that, where a party’s own interest in secrecy could be established, then the situation would be analogous to that of a non-disclosure agreement between the parties involved.

In T 830/90 (OJ 1994, 713) the board, faced with the facts of the case, took the view that a confidentiality agreement had - at least implicitly - been reached. This was perfectly sufficient. Furthermore, in line with general experience, it had to be assumed that such an agreement would be observed at least as long as there was a common concern for secrecy. Such concern would last at least for the period required to safeguard the interests of the business partners.

In T 799/91 the opponents asserted that the subject-matter claimed had been in prior public use in that its manufacture had been "sub-contracted out" to a third company. According to the board the third company was not simply any third party because the opponents' decision to place an order was based on a relationship of trust. The board therefore saw no indication of there having been prior public use, nor could the claim have been substantiated by the testimony of any witness.